Relationship between Contrast Enhancement of the Perivascular Space in the Basal Ganglia and Endolymphatic Volume Ratio

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Purpose: We routinely obtain the endolymphatic hydrops (EH) image using heavily T₂-weighted three dimensional-fluid attenuated inversion recovery (hT₂w-3D-FLAIR) imaging at 4 hours after intravenous administration of a single-dose of gadolinium-based contrast media (IV-SD-GBCM). While repeating the examination, we speculated that the contrast enhancement of the perivascular space (PVS) in the basal ganglia might be related to the degree of EH. Therefore, the purpose of this study was to investigate the relationship between the endolymphatic volume ratio (%EL_volume) and the signal intensity of the PVS (SI-PVS).

Materials and Methods: In 20 patients with a suspicion of EH, a heavily T₂-weighted 3D-turbo spin echo sequence for MR cisternography (MRC) and an hT₂w-3D-FLAIR as a positive perilymph image (PPI) were obtained at 4 hours after IV-SD-GBCM. The %EL_volume of the cochlea and the vestibule were measured on the previously reported HYDROPS2-Mi2 image. The PVS in the basal ganglia was segmented on MRC using a region-growing method. The PVS regions were copied and pasted onto the PPI, and the SI-PVS was measured. The larger value of the right and the left ears was employed as the %EL_volume, and the weighted average of both sides was employed as the SI-PVS. The correlation between the %EL_volume and the SI-PVS was evaluated.

Result: There was a strong negative linear correlation between the %EL_volume of the cochlea and the SI-PVS (r = −0.743, P < 0.001); however, there was no significant correlation between the %EL_volume of the vestibule and the SI-PVS (r = −0.267, P = 0.256).

Conclusion: There was a strong negative correlation between the cochlear %EL_volume and the SI-PVS. Contrast enhancement of PVS might be a biomarker of EH.